The invention relates to compositions of matter targeted to antigen-processing cells.
An antigen-processing cell is a leukocyte capable of secreting proteases or reactive-oxygen intermediates, or a leukocyte capable of internalizing and processing a protein, a carbohydrate, a polynucleic acid, or bacterium, and subsequently presenting a processed form thereof on its cell surface. Circulating leukocytes can internalize foreign particles by three mechanisms, the first being active phagocytosis, the second being passive, concentration gradient-dependent adsorption, and the third being active transport. Antigen-processing cells therefore include granulocytes (e.g., eosinophils, or polymorphonuclear neutrophils), macrophages, and monocytes.
In addition to antigen processing, antigen-processing cells perform proliferative and secretory functions. Certain antigen-processing cells circulate throughout the body, via the vascular system. Circulating antigen processing cells may or may not circulate through the lymph system. Examples of circulating antigen-processing cells include eosinophils, polymorphonuclear neutrophils, macrophages, lymphocytes, and monocytes. Examples of non-circulating antigen-processing cells include Kupffer cells in the liver, and microglial cells.